Overlooked coating failures and lax oversight of high-risk corrosion environments top the list of “foreseeable” causes of a massive 2008 gas pipeline explosion in Western Australia, government regulators say.
The rupture, explosion and fires generated by six pipelines on Varanus Island were due to corrosion—a serious risk that was “not only foreseeable but to some extent foreseen” by Apache Energy Ltd., which operates the system.
Photos: Apache Energy
|Six pipelines eventually ruptured in the accident, costing Western Australia nearly a third of its gas supply for two months.|
That is the conclusion of the Offshore Petroleum Safety Regulation Varanus Island Incident Investigation Report, which was just released after Apache lost a three-year legal battle to keep the report secret.
The disaster cut the state’s domestic gas supply by about a third and cost the local economy about $3 billion.
The blast occurred June 3, 2008, when an export sales gas pipeline, “critically weakened” by external corrosion, ruptured at the shoreline. Almost immediately, another 12-inch pipeline a foot away also ruptured, and both pipelines started intense fires.
That was followed by ruptures of a 16-inch, six-inch and two four-inch pipelines closer to the island’s Harriet Joint Venture gas plant, eventually causing $60 million in damage to the facility.
About 150 plant workers were safely evacuated and, thanks in part to wind direction away from the blaze, no one was injured.
Apache, a subsidiary of the U.S.-based Apache Corp., operated the system and was the majority partner in the joint venture.
In devastating detail, the government’s 494-page report describes red flags that Apache should have seen and addressed years before the disaster.
‘Not Only Foreseeable, But Foreseen’
“We found that there was a range of Apache documentation that should have alerted the operator to serious risks involving external corrosion around the shore crossing of the 12 inch SGL, where it ruptured,” the report said.
“We believe that the risk of this occurring was not only foreseeable but to some extent foreseen.”
In addition to a variety of licensing and regulatory lapses, the investigators found:
• Some Apache consultant reports “seemed to understate the risks involved, perhaps because they had not reviewed prior consultancy reports which had already identified corrosion vulnerabilities.”
• Hazard mitigation measures proposed for the network “were inadequate and did not properly assess risks inherent in the pipeline system on the island, especially in the vicinity of shore crossings.”
• Apache’s safety culture “was generally not at the level of being proactive or generative,” with chronic understaffing and accidents seen as “fundamentally surprising events.”
“Overall, the lack of robust corrosion data and prevention systems for the Varanus Island Shore crossing zone of the 12 inch SGL was not addressed prior to the explosion.”
‘Confused and Confusing’
While the risk of a “major accident event from possible external corrosion was clear in Apache’s documentation,” Apache’s understanding of its own cathodic protection system was “confused and confusing,” the report said.
The report noted an incident in 2001, when the then-Department of Industry and Resources found serious external corrosion in Apache’s offshore platform pipework that was discovered only by chance and was linked to a lack of specialist corrosion staff.
|The blasts cost $60 million in damage to the plant on Varanus Island.|
Three years later, sections of concrete coating had fallen away from the pipeline, the agency noted. Four years after that, the pipeline exploded, exposing corrosion and showing inadequate protection from the anti-corrosion coating and the cathodic protection system.
“Apache’s response to this was clearly unsatisfactory,” the report said.
Apache has defended its safety protocols.
Jane Cutler, CEO of Australia’s new National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), said the report provided a further reminder of the risks involved in petroleum operations and the need for vigilance.
“The fortunate fact that no lives were lost in the Varanus Island incident does not detract from the ongoing imperative for industry to ensure it complies with the law in order to protect lives and the environment,” she said.
Cutler noted that findings from the newly unveiled report echoed those delivered by inspectors from the National Offshore Petroleum Safety Authority (NOPSA) in October 2008. The 2008 NOPSA report concluded that there was:
• Ineffective anti-corrosion coatings and ineffective cathodic protection auditing by Apache Energy Ltd., particularly in high-risk corrosion environments affecting sections of the pipeline; and,
• Ineffective inspection and monitoring by Apache Energy Ltd. of sections of the affected gas pipeline.
“The latest report provides another valuable tool in terms of lessons learnt and the obligations of operators to ensure they have appropriate monitoring and inspection regimes in place for their petroleum activities and facilities, including pipelines,” Cutler said.
NOPSEMA was established Jan. 1, 2012, as Australia’s first national independent regulator for safety, well integrity and environmental management for offshore oil and gas operations.